1. Field of the Invention
The present invention relates generally to mechanisms for controlling optical path length within a laser cavity, and particularly to a displacement device in which a PZT stack is provided in a cylindrical container outside the cavity, and a displacement member transmits axial movement of the stack relative to the container, to the optical element (e.g., a partially or fully reflective element) within the cavity.
2. Description of the Prior Art
The known systems provided for stabilizing an optical path length in a laser cavity, wherein lead zirconate titanate (PZT) elements are employed so as to maintain laser frequency stability, have been inherently vibration sensitive in at least one axis and fail to stabilize as they become unstable in the environment. Other problems arose on account of contamination of the laser vacuum area by the PZT elements themselves.
Laser stabilization systems are also known which include bimorph bending elements. Such systems, however, develop only relatively weak forces in the axial direction (i.e., the direction in which the laser mirror is desired to be displaced), so that the systems cannot withstand vibration extremes. Also, since very large forces are not developed, the known systems must be arranged so that the optical element to be stabilized (by controlled axial displacement) is mounted directly to the bending element within the laser cavity area.